Image distortion correction

• US 20090154822A1
• Filed: 12/17/2007
• Published: 06/18/2009
• Est. Priority Date: 12/17/2007
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Lin, Shang-Hung, Cabral, Brian K., Tjandrasuwita, Ignatius
• Granted Patent: US 9,177,368 B2
• Time in Patent Office: Days
• US Class Current: 382/255
• CPC Class Codes: G06T 5/80 Geometric correction

Abstract

Methods and systems for reducing or eliminating distortion in an image are described. The approach generally involves determining the distortion introduced by a lens, and modifying a captured image to reduce that distortion. In one embodiment, the distortion information associated with a lens is determined. The distortion information is stored. A captured image taken by that lens is processed, with reference to the distortion information.

Claims

1. A method of reducing image distortion, comprising:

determining distortion information associated with a lens system;

storing said distortion information;

processing a captured image taken with said lens system, with reference to said distortion information; and

generating a corrected image comprising reduced image distortion compared to said captured image.

2. The method of claim 1, wherein said determining comprises:

taking a calibration picture of a reference image using said lens system; and

calculating said distortion information by comparing said calibration picture with said reference image.

3. The method of claim 2, further comprising:

repeating said taking and said calculating for a plurality of reference images, to determine said distortion information for a plurality of distortion types.

4. The method of claim 1, wherein said generating comprises:

extracting a correction value for a destination pixel in said corrected image from said distortion information;

obtaining a source pixel value from said captured image;

modifying said source pixel value with reference to said correction value to generate said destination pixel; and

repeating said extracting, said obtaining, and said modifying for each of a plurality of destination pixels in said corrected image.

5. The method of claim 4, performed by a shader of a graphics processing unit (GPU).

6. The method of claim 1, wherein said storing comprises:

writing said distortion information as a correction image.

7. The method of claim 6, wherein said correction image comprises a plurality of correctional pixel data.

8. The method of claim 7, wherein said correctional pixel data comprises position translation information.

9. The method of claim 8, wherein said processing comprises:

obtaining a source pixel value from said captured image;

translating said source pixel value from a first location in said captured image to a second location in a corrected image, with reference to said position translation information; and

repeating said obtaining and said translating for a plurality of destination pixels in said corrected image.

10. A system for reducing lens distortion in a captured image, comprising:

a buffer for storing information; and

a texturing engine for generating pixel data, wherein said texturing engine is configured to access a correction image stored in said buffer, and use said correction image to generate a corrected image from said captured image.

11. The system of claim 10, wherein said texturing engine comprises a plurality of pixel shaders.

12. The system of claim 11, wherein each of said plurality of pixel shaders is configured to generate a corrected pixel in said corrected image.

13. The system of claim 12, wherein said plurality of pixel shaders are configured to generate said corrected pixel by obtaining a correction value from said correction image for said corrected pixel, obtaining a source pixel from said captured image, and modifying said source pixel with reference to said correction value to generate said corrected pixel.

14. The system of claim 10, further comprising a camera with a lens system for providing said captured image, and wherein said correction image comprises a two dimensional image.

15. The system of claim 10, wherein said correction image comprises a plurality of separable one-dimensional images.

16. The system of claim 10, wherein said correction image comprises a one-dimensional radial image.

17. A computer-readable medium having computer-readable program code embodied therein for causing a computer system to execute a method of warping a captured image to reduce distortion therein, said method comprising:

generating distortion correction information;

storing said distortion correction information as a warping texture;

loading said warping texture into a graphics processing unit (GPU); and

producing a modified image by using said GPU to warp said captured image with reference to said warping texture.

18. The computer-readable medium of claim 17, wherein said distortion correction information comprises absolute pixel correction information.

19. The computer-readable medium of claim 17, wherein said distortion correction information comprises relative pixel correction information.

20. The computer-readable medium of claim 17, wherein said using said GPU comprises:

assigning a pixel shader to generate a destination pixel in said modified image;

using said pixel shader and said destination pixel to obtain a correction value corresponding to said destination pixel from said warping texture;

using said to associate her and said correction value to obtain a source pixel from said captured image; and

outputting said source pixel as said destination pixel.